Evaluation of multipath mitigation performance using signal-to-noise ratio (SNR) based signal selection methods

Satellite signal strength sometimes decreases when multipath exists. This effect reduces signal quality and can lead to a large static positioning error, even the survey-grade receivers are used. Three signal selection methods based on signal-to-noise ratio (SNR) measurements were proposed. The first was the conventional method, based on elevation-dependent average SNR, the second used a moving average of SNR fluctuation and the third method used NLOS exclusion based on SNR residual clustering by the K-means algorithm. To evaluate the positioning accuracy improvement, the static 1 Hz single-point positioning (SPP) test was performed in real-time in two different multipath environments using both dual and quad- constellation GNSS receivers. Trimble and CHC receivers were used at each point to examine the effect on each measurement. Results indicated that the three proposed methods mainly reduced multipath error in horizontal direction compared with the normal SPP.